Too much rain slows start of MPCA’s water monitoring season

600: That’s the number of sites the Minnesota Pollution Control Agency’s (MPCA) biological water monitoring staff planned to test this summer.

96: That’s the number of sites monitored so far; it should be closer to 250.

The extreme rain events in June have hampered the MPCA’s water quality monitoring efforts across the state, but hit particularly hard is southern Minnesota where many cities have severe flooding.

Dan Helwig, MPCA surface water monitoring supervisor, believes the agency’s monitoring objectives may be hard to meet this year. “Normally, we can deal with high water by moving sampling operations to watersheds with less rain. However, the high amounts of rain statewide have limited the ability of the crews to adjust and move because many places are experiencing high water levels.” Protocol dictates that the MPCA sample when conditions are near the average flow because sampling during drought or flooding conditions can give skewed results.

High flow events can have negative impacts on stream biology because of increased pollutant loads, like nitrogen and phosphorus, as well as stream chemistry changes. These impacts can be both natural (e.g., low dissolved oxygen in streams due to the influx of water from wetlands) and aggravated by poor land use practices (e.g., increase in contaminants and sediment due to poor stream buffers).

What does this setback mean for the MPCA? Right now it means the monitoring crews in the hardest hit parts of the state have to wait. According to Helwig, “At this point, even if we can get our water levels back to average, we may not be able to catch up. And, if there are more delays, there’s a good chance we will have impacts across our entire water program.”

The MPCA works on a watershed approach, which is a 10-year monitoring cycle schedule. Each of the state’s 81 watersheds is monitored sometime in that 10-year timeframe and the monitoring results set the foundation for future work within each watershed. If the monitoring schedule is disrupted, other work that depends on that data, like waterbody assessments and restoration and protection plans, will also be affected.